No, HTML will not do the trick. You will need a more flexible server side language. For simplicity purposes, you could use a download manager such as Zen Cart or PayPal Download Manager (not from paypal).

The simpler method is to have a success page that the user would land on when the purchase is complete. When the users visits this page, get their email via POST and send the product to them via the mail() function in PHP. Perform validation on the user to assure that they actually purchased the product, or rather - that the payment was successful.

You may want to hire a freelance web developer to develop a payment portal if Zen Cart isn't right for you.